An electrostatic chuck holds a semiconductor wafer onto a pedestal using electrostatic attraction inside a plasma reactor chamber. In a plasma etching apparatus, wafers are cooled so as not to be damaged due to the high temperature caused by the plasma. In this regard, it is desirable to circulate a coolant between the electrostatic chuck and the wafer. Heretofore, a variety of methods have been utilized to accomplish this. In some systems, grooves are machined into a pedestal and an insulated copper foil is placed over the same to provide channels or grooves for the flow of a gas coolant which is supplied through a port formed in the pedestal. Another method involves applying an insulated conductive element on a pedestal and etching grooves in the top surface of the insulative layer to again provide coolant grooves or channels for a gas such as helium. Yet another method is to selectively apply isolated strips of an insulative material such as polyimide on a flat pedestal and overlay a conductive foil on the same to produce a surface with raised features caused by the selectively placed insulative strips. The raised features elevate the semiconductive wafer and define a pooling area for the cooling gas. These systems are expensive and complicated to assemble.
The present invention provides advantages and alternatives to the prior art.